In many transmitter, receiver or transceiver applications, a local oscillator (LO) signal is used, for instance, for up-mixing or down-mixing a signal to be transmitted. Digital-to-time converters (DTC) may, for instance, be used to generate these modulated or unmodulated local oscillator signals. The digital-to-time converters may be used as delay circuits to control, for instance, the phase of the corresponding oscillating signals. Depending on the application, for instance, depending on the modulation scheme used, the requirements concerning the linearity of the digital-to-time converter may be crucial. Since a digital-to-time converter operates directly on a phase-sensitive signal, filtering the DTC output signal may not be a viable step, which may even further increase a need to linearize the digital-to-time converter.
One way to lower the linearity requirement on such a circuit is the concept of pre-distortion, which may be applied to a control signal input of the digital-to-time converter. In this case, measured non-linearity values may be used to counteract the non-linearity of the digital-to-time converter. However, this may require an exact calibration of the digital-to-time converter to a very high degree.
Also in other technical fields, digital-to-time converters may be used, for instance as delaying circuits, but also for other purposes. For instance, digital-to-time converters may be used in measurement applications, synchronization applications and other applications to name just a few. Also in these applications the linearity of the digital-to-time converter may directly influence the application.
Also in these fields a technique similar to the previously-mentioned pre-distortion technique may be used to counteract at least partially of the digital-to-time converters. Also for these applications calibration data for the digital-to-time converters may be useful to increase the accuracy of the results achieved.